Jflex is not recognized as an internal or external command operable program or batch file

Q: How do I fix Java not recognized?

Here are the three easiest ways to fix Javas not recognized as an internal or external command” error:.

Recently, ive turned to Matlab as a simplistic language to extra computation information from an application. But to do this I needed to analyze the source code and build a dependency flow graph to represent the data dependencies between computations.

Inhaltsverzeichnis Show

Why the Not Recognized as an Internal or External Command Error Occurs?
How to Fix the "Not Recognized as an Internal or External Command" Error
1. Verify if the Program Is Installed
2. Use the Full File Path to Execute the Command
3. Use the Full File Path Within Double Quotes
4. Add the File Path to the Windows Environment Variables
5. Move Files to System32 Folder
Fixing the CMD Not Recognized as an Internal or External Command Error
How do I fix Java not recognized?
Why is Java not showing up in command prompt?

The simplest solution: a custom compiler.

I chose to use Flex & Bison since it would allow me to use these tools in either windows or a linux environment. So first we’ll go over where to go to get the install files and then the installation & configuration.

To get the Flex windows installer head over to http://gnuwin32.sourceforge.net/packages/flex.htm and pick a download that suits your needs, although ill be using the “Complete package, except sources”. As you install the tool, be sure to choose an installation directory with NO SPACES in any of the folder names, i’ll be installing to “C:\GnuWin32”. At this point if you open a command window and type “flex” you should see: “‘flex’ is not recognized as an internal or external command, operable program or batch file.” This is because we need to add the folder containing the binary files (“C:\GnuWin32\bin”) that were just installed to the PATH system variable. After doing so, close the current cmd window and open a new one and try again. You should not see an error now (press CTRL+C to quit flex).

Pretty much the same procedure for Bison, head to http://gnuwin32.sourceforge.net/packages/bison.htm for the download. Install to the same directory as above, and then type “bison” in the same cmd window (you dont have to close it and reopen it since the PATH does not have to be modified since the binaries are in the same folder), you should see: “bison: missing operand after ‘bison’ Try ‘bison –help’ for more information.” Congrats! Youve just setup Flex and Bison on windows!

The Command Prompt in Windows is a handy utility. It allows you to perform many tasks quickly; however, the command processor may show the "not recognized as an internal or external command" error when you try to execute a command.

It is a common error and usually occurs due to incorrect command execution. This article explains the causes and a few troubleshooting steps to help you fix this error.

Why the Not Recognized as an Internal or External Command Error Occurs?

Windows OS keeps a list of paths known as Windows Environment Variables to launch and execute programs quickly. Any issues with it can cause the error.

Potential issues that cause this error include:

Incorrect commands.
Registry entries interrupting the functioning of commands and more.
Executable programs or scripts not installed.
An incorrectly specified path or filename.
A missing file directory in Windows Environment Variables.

How to Fix the "Not Recognized as an Internal or External Command" Error

This error is often triggered when you run a program or CMD command, and something goes wrong. We have listed fixes for both versions of the error, so follow the relevant one to your case.

1. Verify if the Program Is Installed

control panel installed programs

Command Prompt can’t run a program that does not exist. If you are trying to execute a newly installed program, ensure it is correctly installed.

To verify the installation:

Press Win + R to open Run. Then, type control and click OK.
Then, in the Control Panel, go to Programs > Programs and Features.
Scroll through the list of installed apps and locate the app you want to run.

Alternatively, you can also view installed apps by accessing Apps and Features in Settings. To do this, press Windows key + I, click on Apps and locate the installed app.

By default, when you try to launch a program or a script from CMD, the command processor looks for the related files and paths in the System32 folder or environment variables. If the file is missing, it will return the not recognized as an internal or external command, operable program, or batch file error.

This is likely because Windows does not install most apps in the System32 folder, but C:\Program Files instead.

You can resolve this issue in three ways:

First, use the full path of the executable file to launch the program.
Second, add the program path to Windows environment variables.
Finally, move the files to the System32 folder.

2. Use the Full File Path to Execute the Command

run programs using full file path

First, let's try the full path method. Here, we will use the full file path instead of the app name to launch programs from Command Prompt. Here's how to do it:

First, open the Command Prompt as administrator.
Next, type the full path of the application you want to launch. For example, if you want to open the ESBCalc Port located in the C:\ directory, then the command to open the app with the full path will look something like this:C:\ESBCalcPort.exe
That said, this will only work if the file path does not have any white spaces. If your file path has a space, type the file path inside double-quotes.

3. Use the Full File Path Within Double Quotes

launch internet explorer double quotes cmd

Command Prompt reads the white spaces as the end of a command and treats anything after the space as a separate command.

Let’s say you want to launch the Internet Explorer app located in C:\Program Files\Internet Explorer\iexplore.exe via CMD. However, running this file path will return an error due to the space between Program Files and Internet Explorer.

To avoid this, you can insert the file path within a double quote. Here, the command to launch Internet Explorer will look like this:

"C:\Program Files\Internet Explorer\iexplore.exe"

4. Add the File Path to the Windows Environment Variables

You can edit the Environment Variables and add the file path of your application to its directory. This way, Command Prompt will identify the path for the entered command and execute it without the error.

Adding a full file path to the Windows Environment Variable can help you resolve the not recognized as an internal or external command error for the Flex, nmake, make, cobra, Is, terraform, gcc, code, Android Studio, Python, Fastboot, and ADB commands.

To edit Windows Environment Variable:

Press Win + R to open Run.
Next, type control and click OK to open the Control Panel.
Go to System and Security > System. In the left pane, click on Advanced System Settings.
On newer versions of Windows 10, go to Settings > System > About. Then, click on Advanced system settings underthe Related settings section.
In the Advanced tab, click on the Environment Variables button.
In the new window, under System variables, select the Path variable.
Click the Edit button.
In the Edit window, click on New.
Here, you have to paste the program's file path you want to run from CMD. For example, if you want to run the Chrome browser located in C:\Program Files\Google\Chrome\Application, then the full file path will look like this:C:\Program Files\Google\Chrome\Application
Click OK to add it to the Environment Variables.
Then, click OK on all open windows to save the changes.

Once you have added the new environment variable, open Command Prompt, enter the program's name, and CMD will open it without any error.

5. Move Files to System32 Folder

move chrome files system32 folder

System32 is a protected system folder, and it is protected for a good reason. When you try to launch a program as an administrator, Command Prompt looks for the executable file in the System32 folder. However, since all the programs are not installed in the System32 folder, you may end up with an error.

If you still want to run the program from CMD and don’t want to type a full file path, you can move the program files to the System32 folder.

To move program files to the System32 folder:

Navigate to the installation directory for your program and copy all the files in the folder. Here, we will move Google Chrome files located in C:\Program Files\Google\Chrome\Application to the System32 folder.
Next, navigate to the C:\Windows\System32 folder and paste the copied files. Click Yes if a UAC prompt appears.
Next, open the Command Prompt as administrator, type chrome, and hit enter. CMD will instantly open the Google Chrome browser.

Fixing the CMD Not Recognized as an Internal or External Command Error

Command Prompt commands are not case-sensitive, but it does not forgive of extra spaces. To resolve this error, check if the commands are correct and use file paths with spaces within double-quotes. For the programs not installed in the System32 folder, add an environment variable with your application’s full file path to launch apps through CMD.

How do I fix Java not recognized?

Here are the three easiest ways to fix Java's “not recognized as an internal or external command” error:.

Install or reinstall Java and the JDK on your computer..

Add Java's bin directory to the computer's PATH..

Restart the command prompt, terminal window or PowerShell..

Why is Java not showing up in command prompt?

when trying to run the java command, this means that there is no java command on your shell's command search path. The cause could be: you don't have a Java JRE or JDK installed at all, you have not updated the PATH environment variable (correctly) in your shell initialization file, or.